summaryrefslogtreecommitdiff
path: root/src/stdio/fseek.c
AgeCommit message (Collapse)AuthorLines
2018-09-16fix null pointer subtraction and comparison in stdioRich Felker-2/+2
morally, for null pointers a and b, a-b, a<b, and a>b should all be defined as 0; however, C does not define any of them. the stdio implementation makes heavy use of such pointer comparison and subtraction for buffer logic, and also uses null pos/base/end pointers to indicate that the FILE is not in the corresponding (read or write) mode ready for accesses through the buffer. all of the comparisons are fixed trivially by using != in place of the relational operators, since the opposite relation (e.g. pos>end) is logically impossible. the subtractions have been reviewed to check that they are conditional the stream being in the appropriate reading- or writing-through-buffer mode, with checks added where needed. in fgets and getdelim, the checks added should improve performance for unbuffered streams by avoiding a do-nothing call to memchr, and should be negligible for buffered streams.
2018-09-12remove spurious inclusion of libc.h for LFS64 ABI aliasesRich Felker-2/+1
the LFS64 macro was not self-documenting and barely saved any characters. simply use weak_alias directly so that it's clear what's being done, and doesn't depend on a header to provide a strange macro.
2018-09-12reduce spurious inclusion of libc.hRich Felker-0/+1
libc.h was intended to be a header for access to global libc state and related interfaces, but ended up included all over the place because it was the way to get the weak_alias macro. most of the inclusions removed here are places where weak_alias was needed. a few were recently introduced for hidden. some go all the way back to when libc.h defined CANCELPT_BEGIN and _END, and all (wrongly implemented) cancellation points had to include it. remaining spurious users are mostly callers of the LOCK/UNLOCK macros and files that use the LFS64 macro to define the awful *64 aliases. in a few places, new inclusion of libc.h is added because several internal headers no longer implicitly include libc.h. declarations for __lockfile and __unlockfile are moved from libc.h to stdio_impl.h so that the latter does not need libc.h. putting them in libc.h made no sense at all, since the macros in stdio_impl.h are needed to use them correctly anyway.
2011-04-02apparently fseek should not set the error flag on failed seekRich Felker-4/+1
2011-03-28major stdio overhaul, using readv/writev, plus other changesRich Felker-6/+14
the biggest change in this commit is that stdio now uses readv to fill the caller's buffer and the FILE buffer with a single syscall, and likewise writev to flush the FILE buffer and write out the caller's buffer in a single syscall. making this change required fundamental architectural changes to stdio, so i also made a number of other improvements in the process: - the implementation no longer assumes that further io will fail following errors, and no longer blocks io when the error flag is set (though the latter could easily be changed back if desired) - unbuffered mode is no longer implemented as a one-byte buffer. as a consequence, scanf unreading has to use ungetc, to the unget buffer has been enlarged to hold at least 2 wide characters. - the FILE structure has been rearranged to maintain the locations of the fields that might be used in glibc getc/putc type macros, while shrinking the structure to save some space. - error cases for fflush, fseek, etc. should be more correct. - library-internal macros are used for getc_unlocked and putc_unlocked now, eliminating some ugly code duplication. __uflow and __overflow are no longer used anywhere but these macros. switch to read or write mode is also separated so the code can be better shared, e.g. with ungetc. - lots of other small things.
2011-02-12initial check-in, version 0.5.0v0.5.0Rich Felker-0/+38